Tanning with d&#39;-methoxy-d-hydroxymethyl diglycollic aldehyde



Patented June 13, 1944 OFFICE TANNING WITH D -METHOXY-D-HYDROXY- METHYL DIGLYCOLLIC ALDEHYDE Kenneth L. Howard, Old Greenwich. Conn. as-

signor to American Cyanamid Company, New York, N. Y.. a corporation of Maine No Drawing. Application August 2, 1943, Serial No. 497,058

1 Claim. (Cl. 8-94.33)

This invention relates to the taming of hides and skins for the production of leather by the application thereto of a new taming agent.

More particularly, the invention deals with the degras or with sulfonated vegetable oils to pro duce soft and well-tanned leather. My invention is particularly well suited for the production of lightleathers from calf skins, kid, sheep and other hides of relatively light weight. The tanning is carried out simply by contacting the hides or skins, preferably in an unhaired and bated condition, with an aqueous solution of the tanning agent for a sufilcient time to complete the tanning.

D methoxy D-hydroxymethyl diglycollic aldehyde has the structural formula:

To the best of my knowledge, it is the first sugar dialdehyde that has shown satisfactory tanning properties. It is prepared according to known methods by the oxidation of alpha-methyl glucopyranoside with lead tetraacetate, and since the alpha-methyl glucopyranoside is readily obtainable from dextrose by the addition of methyl alcohol it is evident that the tanning agent is four hours.

readily obtainable in large quantities from relatively cheap raw materials.

My invention will be further illustrated by the following specific example to which, however, it is not limited.

Example Depickled kid skins having a. pH of 4.0-6.5 were immersed in solutions containing 200% of water, 6% of salt and 7-15% of D'-methoxy- D-hydroxymethyl diglycollic aldehyde, all based on the weight of the skins. The skins were agitated in this solution for 8 hours, or until the tannage was complete, after which they were washed with water and dried. The dried leather was a light pink in color, but upon storage for several days this became a light tan.

The D-methoxy- D-hydroxymethyl diglycollic aldehyde was prepared by the following process: 250 parts by weight of dextrose were heated with 440 parts by weight of benzene in a dehydrating apparatus for 2.5 hours, which resulted in the removal of 21.8 parts of water. After removing the benzene the dry residue was dissolved in 360 parts by weight of absolute methanol to which 15 parts of dry hydrogen chloride had been added and heated under a reflux condenser for 6 parts of decolorizing carbon were then added and the boiling continued minutes longer. The solution was filtered hot, cooled to 5 C., and the alpha-methyl glucopyranoside recovered by crystallization.

25 parts by weight of the glucopyranoside were dissolved in parts of water and 22 parts of lead tetraacetate in 52 parts of glacial acetic acid were added while maintaining the temperature below 40 C. An additional parts of lead tetraacetate were then added over a 45 minute period'after which the solution was stirred for one hour. The solution was decanted and treated with sulfuric acid to precipitate lead, filtered, and the filtrate evaporated under reduced pressure at 40-50 C.

Equally good results were obtained by oxidizing the alpha-methyl glucopyranoside with Pb3o-i in glacial acetic acid.

What I claim is:

A method of tanning hides and skins which comprises impregnating them with a solution containing D'-methoxy-D-hydroxymethyl diglycollic aldehyde.

KENNETH L. HOWARD. 

